Yeah i agree some what! I have rebuilt a few turbos over the years! And found even though i have fitted new bearings etc they was still abit of shaft play due to the turbin shaft haveing alittle wear along with the caseing! Also some turbos i have rebuilt havent had any shaft play what so ever but when takeing them apart and cleaning the carbon from around the turbin piston ring and the housing etc when putting it back together the shaft had alittle play where befor i took it apart it didnt have any at all! The carbon built up froms a little lip if you like on the shaft/housing and when you clean/remove that carbon thats when it gives that few mm of play as im sure you already know! It is always best to get the balancing checked after all you dont want that turbo going tits up on a newly forged engine or any engine infact!